Various compact fragrance diffusers are known in the art.
These compact diffusers most often comprise a reservoir for substances in the liquid state evaporated by atomization of the liquid via a nozzle by means of the Venturi effect. In some sophisticated diffusers, evaporation is facilitated by the application of acoustic vibrations at high frequencies, the effect of which is to reduce the size of the vapor droplets and therefore to increase the area of the liquid in contact with the air and thus improve the diffusion of the fragrance.
In some other diffusers, the fragrance molecules are incorporated beforehand into solid supports, for example polymers. The substances are diffused into the air by heating these solid supports and/or by means of a flow of air over the surface of these solid supports, which techniques have the effect of progressively detaching the fragrance molecules from the solid supports and diffusing them into the surrounding air.
In the field of fragrance diffusion, a distinction is drawn between diffusers adapted to diffuse a single fragrance and diffusers adapted to diffuse a plurality of different fragrances. The expressions single-fragrance and multi-fragrance diffusers are used.
Multi-fragrance diffusers are most often designed to diffuse only one fragrance at a time. The selection of the fragrance to be diffused is the result of a choice made by the user or is controlled by electronic data processing or audiovisual means in the context of multi-sensorial multimedia works. These multi-fragrance diffusers are relatively complex to design and relatively costly.
Multi-fragrance diffusers come up against the difficulty of avoiding cross-fragrance pollution caused by migration of olfactory molecules between the different fragrance reservoirs or contamination or impregnation of components of the diffuser by the different olfactory molecules. The problem arises from the fact that any fragrance, even a dry fragrance, i.e. one integrated onto a solid support, is made up of molecules that coat or impregnate the materials that constitute the diffuser. These materials may then be qualified as reactive to the fragrances; this is the case with most plastics, for example. Now, it is known that mixing a plurality of fragrances is incompatible with the required subtlety of the odors.
By impregnating the components of a diffuser with fragrance molecules is meant here the action whereby fragrance molecules that come into contact with said components penetrate them and diffuse into them.
The document FR02620622A1 proposes a solution to the problem of cross-fragrance pollution in a multi-fragrance diffuser. That document describes a cartridge structured as a plurality of absorbent areas that are soaked in a liquid, the areas being separated from one another by non-adsorbent elements to prevent the migration of different fragrance molecules between areas. The above document does not discuss pollution between the soaked areas and the rest of the diffuser.
In the case of single-fragrance diffusers, migration of fragrance molecules to or impregnation of fragrance molecules into the components of the diffuser does not cause any cross-fragrance pollution problem if they always diffuse the same fragrance, which is the most frequent situation. Once empty, the diffuser is either thrown away or refilled with the same liquid or solid supports impregnated with the same substance.
The cross-fragrance pollution problem arises in the case of single-fragrance diffusers designed to diffuse sequentially a plurality of different fragrances, chosen by the user, because the olfactory molecules of a first fragrance migrate from the liquid reservoir or the impregnated solid supports to the various components of the diffuser and coat them. Consequently, when the user substitutes a second fragrance for a first fragrance, the second fragrance will be polluted by the residue of the first fragrance.
A solution to this problem is described in the document EP1054697 in which the volatile substance is contained in a reservoir one face of which is of spherical shape to enable it to be isolated by rotating the reservoir when odor diffusion is not required. This diffuser has the following drawbacks: the size of the diffuser is necessarily large in relation to that of the active olfactory part because the latter is contained in a small part of a cylindrical channel in an element of orbicular shape; the orbicular shape and the sealing effect of the spherical surface are relatively complex to produce. In the final analysis, the diffuser described in the above document is very complex, relatively bulky and relatively costly.
Also known is a single-fragrance diffuser developed by the company ScentAir and marketed under the trade name ScentWave®. This diffuser comprises a ventilation corridor, a fan and a fragrance reservoir. The fans equipping this type of diffuser are generally cheap fans with plastic material blades that easily become coated with fragrance molecules. For what it's worth, the problem of pollution between fragrances diffused consecutively does not arise in this diffuser because the ventilation corridor, the fan and the fragrance reservoir are fastened together and form an assembly, one assembly being substituted for another to change the fragrance to be diffused or to refill the diffuser with fragrance. Clearly said assembly constitutes a refill that is complex to design and relatively costly.